Explosive



Aug. 28, 1956 J. A. RUTH 2,760,434

EXPLOSIVE Filed Jan. 10, 1952 INVENTOR. JOHN A. Ru TH Maw AGE/VTEXPLOSIVE John A. Ruth, Clinton, Ind., assignor to Olin MathiesonChemical Corporation, a corporation of Virginia Application January 10,1952, Serial No. 265,830 2 Claims. (01. 102-20) This invention relatesgenerally to explosives and more particularly to novel explosive shapedcharges having improved properties.

It has been known in the blasting art that the energy developed by anexplosive charge can be concentrated and a greater depth of penetrationachieved by modifying the shape of the surface of the charge which facesthe media to be blasted. For instance, the surface is provided with acavity therein which may be conical, pyramidal, parabolic or the like;charges having such cavities being referred to hereinafter as shapedcharges. This phenomenon is advantageous in numerous blasting operationssuch as, for example, in perforating the casing and media surroundingoil well bore holes, in some mining operations, tapping metallurgicalfurnaces and in armor piercing projectiles. In some of these operationsthe media must be penetrated to a relatively great depth withoutdestruction tates atent of a large area of the surface thereof and, inmost instances, the blasting must be accomplished with a relativelysmall explosive charge. It has also been known that even greaterpenetration is attained with shaped explosive charges provided with anon-explosive covering or liner conforming to the shaped surfacethereof. This improvement has been attributed to the projection ofparticles of the liner at a high velocity when the explosive is fired.The shaped charges utilized in blasting operations of this type havebeen formed theretofore from secondary explosive compositions having arelatively high degree of bri-sance such as trinitrotoluene,pentaerythritol tetranitrate, cyclotrimethylenetrinitramine or mixturesthereof. While the foregoing explosives have been used extensivelybecause of their relatively high brisance, it has long been recognizedthat greater penetration than is obtainable with shaped charges of theseexplosives would be advantageous in any of the foregoing types ofblasting operations and particularly so in the perforation of oil wellbore holes and in armor piercing projectiles where maximum depth ofpenetration per unit amount of explosive charge is important.

It is an object of this invention therefore to provide an improvedexplosive charge having improved penetrating properties. Still anotherobject of this invention is to provide an improved method forperforating the walls of oil well bore holes. A further object of thisinvention is to provide novel explosive shaped charges. It is a stillfurther object of this invention to provide explosive charges of highbrisance and a method for using them.

In accordance with this invention, the foregoing objects as well asothers which will become apparent from the following description areaccomplished by providing methylenedinitramine as an explosive.Methylenedinitramine in granular or crystalline form can be formedreadily into shaped charges by the methods used heretofore with granulartrinin-otoluene and the like and the resulting charge has greatpenetrating power and other advantages, which will become apparent fromthe detail description hereinafter. This invention further contemplatesan improved process for perforating various media such as, for

instance, the wall of oil well bore holes, armor and similar materialswith shaped charges of methylenedinitramine.

Methylenedinitramine can be prepared by a series of reactions in whichmethylenebis-N-acetamide, methylenebis-N-acetarnide mononitrate,methylenebis-N-(N-nitro) acetamide, the barium salt ofmethylenedinitramine and finally methylenedinitramine are formed in thatorder, in accordance with the process described by Brain and Lambertonpublished in the Journal of the Chemical Society, June 1949, pp. 1633-5.

The surface of the methylene dinitramine charge facing the medium to beperforated is modified to concentrate the energy developed by theexplosion thereof in the known manner, the particular configuration mostadvantageous varying with the type of operation in which the charge willbe utilized. An explosive charge having a cavity in the shape of aninverted cone in a surface thereof is particularly advantageous intapping metallurgical furnaces. Armour piercing projectiles containingshaped charges of methylened-initramine in which the cavity is parabolicare particularly effective. In each instance it is preferred that thecavity in the charge be provided with a nonexplosive covering or liner.The liner may be made from metal, ceramic, plastic or similarnon-explosive material and should conform substantially to the shapedsurface of the explosive charge.

In order to more fully describe and to clarify this in vention, thefollowing is a description of one embodiment thereof:

Referring to the accompanying drawing, a longitudinal sectional view ofan oil well casing 16 is shown with a perforating device 13 positionedtherein and substantially adjacent to the wall 12 of the casing 16. Theperforating device 13 is composed of two external glass parts 1 and 3.The base portion ll contains a relativelysmall pressed explosive charge5 of methylenedinitramine crystals separated from the larger pressedcharge 10 of wax coated met-hylenedinitramine crystals by means of apaper disk 6. The coating of wax is applied to the methylenedinitrarninecrystals to be used for charge 10 by a process which comprises mixing asolution containing about two parts of a microcrystalline petroleum waxknown to the trade as Superla N o. 3 Special and which has a meltingpoint of about 76 C. dissolved in about 80 parts by weight carbontetrachloride with about 50 parts methylenedinitramine and evaporatingthe carbon tetrachloride therefrom by means of an air steam. A conicalshaped cavity is formed in the surface of charge 10 and covered with abrass liner 7. The flange 4 of the open end of the base portion 1 of thedevice 13 is coated with a layer of pitch 1'7 and inserted into theflange 18 of nose portion 3 forming a friction fit and water-proofjuncture therewith. The ogive 19 of nose portion 3 of the perforatingdevice 13 extends through an opening in aluminum foil 8 and is supportedthereby. A primac-ord 9 extends through opening H in aluminum foil 8 andaround the base portion 3 between protuberances 2 and 15 and is drawntightly through-opening 14 in aluminum foil 8, thus supporting andexerting pressure against the base portion 1 of the device 13 andwedging the entire assembly in position with respect to the aluminumfoil 8. When it is desired to fire the methylenedinitramine charges 5and 10 the primacord 9 is initiated by means of a co ventional electricdetonator or any other suitable means which initiates untreated charge 5of methylenedinitramine which fires the main charge 10. A jet of metalfrom liner 7 as well as the energy developed by the explosive charges 5and M are projected against the wall 12 of casing 16 perforating it andpenetrating into the media thereabout.

It has been found that methylenedinitramine shaped in the Ballistic'Mor-tar tion of methylcnedinitramine at a.

: charges have greater penetrating properties than any of the explosivesdisclosedfor this purposepMethylenedinitrarnine has been. found to havea strength of about 1.5 as compared to 1.6- for trinitrotoiuene asdetermined. and a brisance of about two i times that of trinitrotoluenein the Lead Block or 'irauzl Block'Test. The packing density ofmethylenedinitra- 9 property thereof as a highdetonation rate isadvantageous in blasting operationsutilizing shaped charges. i

As indicated hereinbefore, shaped charges of meth ylenedinitramine aresuperior to the explosives heretofore proposed for tapping metallurgicalfurnaces. In tapping I furnaces with explosiveshaped charges, a hole isusually drilled entirely throught'he fire clay plug in the tap hole. I

This leaves only .arelatively thinbarrier of solid metal adjacent'theinner end of the plug to'preventjfiow of the i The shaped charge is. Irammedinto the holethus formed in the plug and initi ated in perforatethe solid metal incrustation.

molten metal from the furnace.

The ex- 9 of large surfacearea of the medium to be perforated or plosivecharge is usually insulated .by covering it with insulating materialorbyramming insulating material into theholeprior to insertion of theexplosive. 1

g I I When inethylenedinitramine shaped charges are utilized isnotnecessary to drill entirely through the fire clay as these charg'eswill penetrate, an appreciable thickness of the clay as well as thesoiid metal. Usually,depen'ding upon the size of charge used, the holeabout two-thirds of the thickness of the plug thus leaving an addedbarrier against how of, the molten metai and reducing the hazardinvolved in these processes; The

' me'thylenedinitramine can be initiated by the heat from the furnace ora detonator can be embcddedin the charge and ignited electrically toinitiate the explosion thereof, if desired. The methylenedinitramineshaped charge can be formed by pressing into a suitable containerprovided with a concave surface and insulated in accordance withconventional methods.

Methylenedinitrarnine because of its increased penetrating propertiescan also be used advantageously in armor piercing projectiles providedwith a concave surface at the striking end thereof and also for formingdrill holes or channels in mine walls for blasting cartridges.

Numerous variations from the details of the foregoing embodiments suchas, for example, forming the perforating device from plastic or metal,or substituting other types of containers for the perforating device canbe made Without departing from the spirit of this invention.

In the embodiment for perforating the media surround ing oil Well boreholes, other means for supporting the perforating device can beprovided, the one described being only a preferred and convenientmethod. In this particular method, however, the primacord serves atwofold purpose of supporting the device 13 as Well as serving toinitiate the methylenedinitramine charges. Likewise, initiating chargesother than methylenedinitramine need extendthrough only utilized as theshaped charge I and can be handled and paraffin waxes such as lead azidemight be utilized for the igniter explosive charge 5. Waxedmethylenedinitramine is preferably impact sensitivity than uncoatedmethylenedinitraminc andshipped with less danger of inadvertentexplosion. 'Uncoated methylenedinitramine can be utilized satisfactorilyprovided caution isobserve'd in handling.

While in the foregoing embodiments microcrystalline petroleum war wasutilized, other Waxes such as ceresin, having a suitable melting. pointof about 70 C. or higher can be substituted therefor.

Waxed methylenedinitramine can be utilized entirely and the more impactsensitive chargereplacedtherebyif sufficient means are providedforinitiatingthe desensitized explosive.

effective whether or not minor amountsof other explosives such ascyclotrirnethylenetrinitramine or pentaerythritol i tetranitrate areincluded. g

It should be apparentfron'i thcforegoing description that this inventionaccomplishes its objects and provides an improved explosive charg'e andan improved process.

wherein greater dcpthof penetration without destruction for penetrationof heavy armor is attained.

Having thus described the invention what is claimed V and desired tosecure by, Letters Patent is:

,1. A shaped charge of inethylenjedinitramine having a was: coating andcompressed to packing density of at least 1.7, and combined therewith asecond charge ofv uncoated 'methylenedinitramine, said shaped chargehaving a strength ofat least 1.5 times as great as that oftrinitrotoluene and a detonation rategreater than that oftrinitrotoluene. g

2. A Well bore hole perforating device comprising a container having abase portion and surface of the methylenedinitr'amine charge facing thenose portion having a cavity therein and a non-explosive liner coveringand in engagement with the surface of said cavity.

References Cited in the file of this patent UNITED STATES PATENTS989,375 Luciani Apr. 11, 1911 2,399,211 Davis et al Apr. 30, 19462,413,680 Blacltington et a1 Jan. 7, 1947 2,415,814 Davis et al Feb. 18,1947 2,494,256 Muskat et al. Ian. 10, 1950 2,563,131 Old Aug. 7, 19512,629,325 Sweetman Feb. 24, 1953 2,649,046 Davis Aug. 18, 1953 FOREIGNPATENTS 574,271 Great Britain Dec. 31, 1945 OTHER REFERENCES ChemicalSociety Journal, 1949, part II, pages 1633 to 1635.

it) because it has a lower Shaped charges of methyle'ne'dinitramine are.

a nose portion fric tionally fittogether, an impact sensitive explosivecharge 1 and a charge ofwax coated methylenedinitramine com pressed to adensity of at least 1.7 in said container, the

2. A WELL BORE HOLE PERFORATING DEVICE COMPRISING A CONTAINER HAVING ABASE PORTION AND A NOSE PORTION FRICTIONALLY FIT TOGETHER, AN IMPACTSENSITIVE EXPLOSIVE CHARGE AND A CHARGE OF WAX COATEDMETHYLENEDINITRAMINE COMPRESSED TO A DENSITY OF AT LEAST 1.7 IN SAIDCONTAINER, THE SURFACE OF THE METHYLENEDINITRAMINE CHARGE FACING THENOSE PORTION HAVING A CAVITY THEREIN AND A NON-EXPLOSIVE LINER COVERINGAND IN ENGAGEMENT WITH THE SURFACE OF SAID CAVITY.